Just Sharing This Another motorised ka band polarity project.

[dreamsat]

I do not know where you saw the picture of Pololu? Maybe from S-Band. He is the only one to whom I have sent this picture. If everything works I will publish it here.

 

[John]

I do not know where you saw the picture of Pololu? Maybe from S-Band. He is the only one to whom I have sent this picture. If everything works I will publish it here.

You PM'd it to me.
** Edit - well i think you did, i'm sure iv'e seen that picture in the last week or so

 

[John]

... a couple of pics showing the preparation and then the handling of my balls with a pair of tweezers !.

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[John]

... stainless ball bearings of course - for the home-brew rotary joint on the 18GHz L/R/H/V project.

 

[Channel Hopper]

... a couple of pics showing the preparation and then the handling of my balls with a pair of tweezers !.

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As you own more than the usual brace, you carry on.

 

[John]

As you own more than the usual brace, you carry on.

... thank you.

 

[scopus]

... a couple of pics showing the preparation and then the handling of my balls with a pair of tweezers !.

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Looks like a right balls up to me....

 

[John]

Looks like a right balls up to me....

... I mention a bit of ball activity on my behalf and everybody's coming out of the closet !!

 

[scopus]

... I mention a bit of ball activity on my behalf and everybody's coming out of the closet !!

Nothing like playing with your balls....

 

[Channel Hopper]

... I mention a bit of ball activity on my behalf and everybody's coming out of the closet !!

Just keeping the tweezer comments from the mainstream.

 

[John]

... More or less finished playing with this little 18GHz - H/V/L/R pol project apart from taking off the temp feed covering due to having a lazer pointer tucked down the feed waveguide whilst aligning the feed up for illumination. It's working surprisingly well to say it's cobbled up from various bits, a home-brew rotory joint, miss-matches on coax adapters etc. I spent a fair while tweeking for best performance and don't think i can improve on it. Did a comparison to see how affective the multi-pol unit was by comparing performance between the two units, a well tweeked Norsat pll lnb fixed in the Vertical pol position looking at the stable 19.2°East Ka Newsnet Comms freq 18561 GHz V and the Multi pol unit, which both are now on the lnb changer on the 1.2 Gibby. The fixed pol has a far simpler signal path with less components in the chain compared to the multi pol unit - see drawing.
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[Llew]

Some interesting experimentation you've done there John. The multi-pol setup gives a decent signal throughput considering the various, possibly lossy components in the path.
My Hughes 18GHz DRO LNB+ FD9000 feedhorn suits me fine at present, but I'm always up for doing Ka-related experiments myself. Unlike you, mostly hacksaw/hammer/blunt drill stuff though

 

[John]

Some interesting experimentation you've done there John. The multi-pol setup gives a decent signal throughput considering the various, possibly lossy components in the path.
My Hughes 18GHz DRO LNB+ FD9000 feedhorn suits me fine at present, but I'm always up for doing Ka-related experiments myself. Unlike you, mostly hacksaw/hammer/blunt drill stuff though

It keeps me off the streets Llew lol. I was quite surprised myself at the results achieved - at first tests, before tweeking the figures were well down and i thought i had a non goer but after careful aligning & tweeking here and there the figures came up - as you know, to get maximum smoke at these frequencies you have to tweek to within + /- 1mm on alignment accuracy.

 

[John]

... More or less finished playing with this little 18GHz - H/V/L/R pol project apart from taking off the temp feed covering due to having a lazer pointer tucked down the feed waveguide whilst aligning the feed up for illumination. It's working surprisingly well to say it's cobbled up from various bits, a home-brew rotory joint, miss-matches on coax adapters etc. I spent a fair while tweeking for best performance and don't think i can improve on it. Did a comparison to see how affective the multi-pol unit was by comparing performance between the two units, a well tweeked Norsat pll lnb fixed in the Vertical pol position looking at the stable 19.2°East Ka Newsnet Comms freq 18561 GHz V and the Multi pol unit, which both are now on the lnb changer on the 1.2 Gibby. The fixed pol has a far simpler signal path with less components in the chain compared to the multi pol unit - see drawing.
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... perhaps aught to clarify due to unclear print that the Promax reading on the bottom pic is 15.9dB and that was the maximum obtained at the time

 

[Channel Hopper]

It keeps me off the streets Llew lol. I was quite surprised myself at the results achieved - at first tests, before tweeking the figures were well down and i thought i had a non goer but after careful aligning & tweeking here and there the figures came up - as you know, to get maximum smoke at these frequencies you have to tweek to within + /- 1mm on alignment accuracy.

How accurate is the DiSEqC 1.2 rotor system on the end of the dish, in terms of repeatability moving clockwise/anticlockwise ?
I can't recall is there is a focussing system on the 5402 receiver, though I have seen one within the SF8008 tuning menu.

 

[John]

How accurate is the DiSEqC 1.2 rotor system on the end of the dish, in terms of repeatability moving clockwise/anticlockwise ?
I can't recall is there is a focussing system on the 5402 receiver, though I have seen one within the SF8008 tuning menu.

Using one of these for changer lnb position but use it manually to align each lnb centre position with a fixed reference point at the centre of the lnb position on the end of the Gibby support arms. It's reasonably accurate and convenient to use but i suspect it's the weakest point of the alignment chain. I'll have a look into using something that has a better/finer nudge tuning i think.
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[John]

... had this bit of a whim this afternoon between the rain showers about returning to an idea i meddled with on a Ku feed some years ago that wasn't all that successful. On my 1.2 Gibby 18GHz L/R/H/V Ka rig i use an 18GHz scalar feed off a Hughes ODU. It very slightly over illuminates but is the best matching feed i have found for this dish up to now. So, with a bit of scrap 20mm wide x 2mm thick ali strip i shaped it around the edge of the Hughes feed with a jubilee clip to hold it in place to bring the feed angle to 70° to suit the Gibby - nothing scientific - just a poke and hope experiment to pass an hour or so. The result was positive without doing any adjustment on focal point tweaking etc but the heavens started to open up again so just put a temp plastic bag over the feed to keep the water out. Certainly worth making a new proper job of one when i feel like it.
Just a few pics and the original comparison note. Test freq was the comms freq - 18.561 V on 19.2°East as it's quite stable.
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